To succeed sneakily with mallice
To venture covertley with intent for a personal gain in an subtle manner (sneeky manor)
ie. when your cat steals your spot on the couch he examplifies the true nature of a sheisty mother fucker
note: chanage the spelling and you are sheisty mother fucker
shut up eat a dick
The origin of "shyster" may be from the German "Scheißer" meaning pooper (MW) or from the old use of "shy" meaning disreputable (OED).
You look really sheisty when you grease your chest.